There is only one way to swing a golf club on a single-Plane with minimal to no rotation of the clubface relative to the plane. That is with a grip that goes up the lifeline of both hands.
IT IS IMPOSSIBLE TO ROTATE A TW0-AXIS GRIP ON A SINGLE PLANE
If the left hand grip is taken below the pisiform bone, it is a TWO-AXIS grip!!
All traditional "tour type" grips of the left hand are below the pisiform bone
Every person promoting Moe Norman being on single-plane is a
It was IMPOSSIBLE for Moe to swing on single-plane because Moe's left hand grip was below the pisiform bone.
Bryson DeChambeau has the preception that he is swinging on a single plane; in fact he swings on six-planes; 1-shoulders, 2-upper arm, 3-forearm, 4-hands, 5-shaft and 6-clubface 90 degrees of rotation.